*{
    margin: 0;
    padding: 0;
}
ul,ol{
    list-style: none;
}

.banner {
    width: 50%;
    margin: auto;
    height: 450px;
    position: relative;
    box-sizing: content-box;
}
.banner img{
    width: 100%;
    height: 100%;
}
/* 图片 */
.banner>ul {
    width: 100%;
    height: 100%;
    position: relative;
}
/* 重叠 */
.banner>ul>li {
    width: 100%;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    transition: opacity .5s linear;
}
/* 第一张 */
.imgbox li:nth-child(1){
    z-index: 3;
}

/* 小按钮 */
.banner>ol {
    width: 250px;
    /* height: 30px; */
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    bottom: 10px;
    display: flex;
    justify-content: space-around;
    align-items: center;
    border-radius: 15px;
    z-index:5;
}

.banner>ol>li {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    cursor: pointer;
    border: 1px solid white;
    background-color: rgba(0, 0, 0, .3);

}

.banner>ol>li.active {
    background-color: orangered;
}

.banner>button {
    border: none;
    width: 40px;
    height: 70px;
    position: absolute;
    top: 50%;
    border-radius: 5px;
    transform: translateY(-50%);
    cursor: pointer;
    z-index: 1000;
    color: red;
    background: url(../images/icon-slides.png);
}

#next {
    right: 0;
    background-position-x: -42px;
}